Shia LaBeouf’s increasingly bizarre antics include proclaiming he wanted to mount a camera on his penis while shooting Lars von Trier’s “Nymphomaniac.”

LaBeouf was in Berlin to debut the film over the weekend, but stormed out of a press conference and then appeared on a red carpet in a tux with a paper bag over his head inscribed with the words “I am not famous anymore.”

“Shia had wanted von Trier to put a camera on his penis while filming, so that audiences could have the full experience,” said an insider, but it would have been too much for viewers. (And for his co-star). The film centers on a beaten woman who recalls her varied erotic experiences.

After LaBeouf inexplicably appeared with the bag on his head, word at the festival spread that he did it to cover a missing tooth that was knocked out in a late-night escapade. But he’d pulled out the tooth himself on the set of the Brad Pitt World War II movie “Fury” as part of a method acting experiment to re-create the life of a soldier.

One studio source said LaBeouf’s ongoing eccentric behavior is costing him roles, and that he was meant to be cast opposite Kate Winslet in upcoming indie film “Triple Nine” by John Hillcoat, who directed him in “Lawless.”

But the actor just signed on for Barry Levinson and Mitch Glazer’s “Rock the Kasbah” — which begins filming in June in Morocco with Bruce Willis, Kate Hudson, Bill Murray and Danny McBride. We hear LaBeouf and McBride play a pair of local arms dealers.

Others suggest that LaBeouf is taking a page from Joaquin Phoenix (who grew a beard and announced he was quitting acting to become a rapper, in a ruse that lasted years), and his whole shtick is part of a “performance art” hoax. Said a source, “Everyone who knows Shia is in on the joke. It’s all part of an act.”

LaBeouf has now launched an LA exhibition called “#IAMSORRY.” He sat at the show in silence and stared Marina Abramovic-style with the same paper bag on his head from Berlin.